Usually yes, if the petition is filed promptly with premium processing and she presents the approval at the port of entry, but the timeline should start immediately and the customer should be told the dependency.
File early, pay for speed, and enter on the approval
For a Canadian citizen the sequence is petition, approval and admission at the port of entry; no consular visa is needed. Preparing the evidence, particularly the document-control exports and the quality director’s statement, typically takes several weeks. Premium processing then gives a decision within a short guaranteed window for the additional fee, and she can present the approval notice with her passport at the border and begin work the same day.
Nine months leaves reasonable room, but the plant should not schedule the re-audit on the assumption that the first petition will be approved without a request for evidence. Build in time to respond to one. Her initial period may be up to three years for an established plant, so the assignment can outlast the re-audit and cover embedding the procedure with the U.S.
inspectors. Hypothetical example: a robotics integrator transfers a technician after eleven months of qualifying work because a U.S. installation cannot wait.
Eleven months does not become a year because the project is urgent. The company should preserve the continuous employment record, choose a filing date after the anniversary, and arrange local coverage until then. It should also count prior L time now, since the five-year ceiling may affect whether a short assignment is worth pursuing.